The invention is a telephone network interface device. Telephone network interface devices were disclosed in U.S. Pat. Nos. 4,488,008, and 4,749,359. The philosophy behind the network interface device is that, in the age of separate ownership of premise wiring by subscriber, means are needed to indicate whether a systems fault is in the portion of the loop owned by the telephone company or other utility or the premise wiring owned by the subscriber. In putting the concept into practice, it has been customary in the industry to provide devices having means for connection with telephone company subscriber loop wiring, premise wiring, and line cord wiring connected to electrical jack plugs.
Since the function of the network interface device is to provide for such connections and to allow individual subscribers to test for faults by temporarily disconnecting their wiring from the telephone company subscriber loop, problems can arise when bare connections are exposed to moisture or other environmental conditions which may degrade performance of the unit.